The proposed research objectives are to examine possibilities that somatostatin, a hypothalamic derived peptide, is a regulator of pituitary and extra-pituitary hormonal secretion. Specifically, is somatostatin a) transported to peripheral endocrine organs via circulation, or b) synthesized and released locally? If a or b can be shown, it is proposed to examine whether somatostatin release can be correlated with physiologic signals modulating release of growth hormones (GH), glucagon and insulin. Effects of pharmacologic agents which perturb neuro-transmitter function will also be examined. These problems will be approached by use of a specific radioimmunoassay for somatostatin. It is proposed to use rat, baboon and man as the experimental models to evaluate the presence of somatostatin in hypophysical portal, regional and peripheral circulations. Metabolic clearance rates for infused somatostatin in the baboon will be calculated. Attempts will be made to correlate somatostatin levels with various physiologic states in which GH, glucagon and insulin secretion is altered. The possibility that aberrant somatostatin release accompanies metabolic disorders such as acromegaly, obesity and diabetes mellitus will be tested. BIBLIOGRAPHIC REFERENCES: Ensinck, J.W., Laschansky, E., Knoeber, M., Johnson, D.G., Benson, J.W., and Goodner, C.J.: Distribution of somatostatin measured by radioimmunoassay. Clin. Res. 24:155A, 1976. Ensinck, J.W., Laschanksy, E., Chideckel, E., Palmer, J.P., and Goodner, C.J.: Somatostatin kinetics during infusion in the baboon. Clin. Res. 24:155A, 1976.